Victoria Beckham says she's done with the Spice Girls "for good" and had no "passion" for the girl group's reunion

So much for "Viva Forever." Victoria Beckham had a good run as Spice Girls standout Posh Spice, but she's done "spicing up her life" with the '90s British girl group. Appearing as the guest editor and cover star of Vogue Paris' December issue, the pop star turned successful fashion designer says she has no "passion" for her former "girl power" persona.

"I realized it was finished for good in 2008, when we reformed for our reunion tour," Beckham, 39, tells the mag (via the Telegraph). "It should have been the best moment of my life, but I just wanted to be elsewhere."

(The singer and her bandmates -- Melanie Brown, a.k.a. Scary Spice; Melanie Chisholm, Sporty Spice; Emma Bunton, Baby Spice; and Geri Halliwell, Ginger Spice -- took a very long hiatus in 2000 but reunited for a 2007-2008 world tour. They also joined forces for the 2012 Summer Olympics closing ceremony in London.)

"It wasn't a lack of respect for the girls or the audience, but the passion just wasn't there," Beckham explains. "By contrast, in my new career, the passion grows every year. I still want more."

Victoria Beckham talks about her days as a Spice Girl in the new issue of French VogueCredit: Inez Van Lamsweerde and Vinoodh Matadin/Vogue Paris

Now an international style icon and fashion mogul, the star blames her Spice Girls fame for her reputation as an unsmiling sourpuss. "I looked moody. But I wasn't! I was shy, not very sure of myself," she tells Vogue Paris.

"I had to invent a character and I thought of that: staring at people and pouting," she continues. "My insecurities helped me create the character in a way. Nowadays, it's like a barrier that comes back whenever I go out in public. That's the way fame has affected me."

Privately, she's much more jovial. In a press release about the new issue, Vogue Paris editor-in-chief Emmanuelle Alt described the married mom of four as "the exact opposite of her public image." She added: "She is spontaneous with a great sense of humor, humble yet at the same time driven by a healthy ambition."